Single-operator-exchange (SOE) or “monorail” catheters are catheters in which only a distal portion of the catheter tracks over a guidewire. Proximal of the distal portion that tracks the guidewire, an SOE catheter and guidewire are separate from one another. This allows the proximal portion of the SOE catheter to be relatively simple, having need of one less lumen than would be required for an over-the-wire catheter that tracks a guidewire over its entire length. An SOE catheter is also useful because, by not tracking the guidewire over its entire length, the catheter and guidewire are more easily moved relative one another, such as during a catheter exchange. One example of an early patent in this area is U.S. Pat. No. 5,156,594 to Keith, the disclosure of which is incorporated by reference.
A drawback for SOE catheters is the difficulty of fabrication. Construction of an SOE device typically involves welding or fusing several lengths of tubing together such that a distal portion of the SOE device includes an additional lumen for receiving a guidewire. A guidewire opening or port is provided to allow a guidewire to be introduced to the guidewire lumen through the guidewire port. A number of different manners for providing the guidewire port joint to a rapid exchange-type of medical device have been suggested, for example, by Fitzmaurice et al., U.S. Pat. No. 6,190,358; Enger, U.S. Pat. No. 5,980,486; Estrada et al., U.S. Pat. No. 6,344,029, and Williams et al., U.S. Pat. No. 6,409,863. Williams et al. is also hereby incorporated by reference. The disclosure of the Keith patent above, incorporated by reference, discloses a crimped hypotube which is then attached to a distal polymer member having a guidewire tube and an outer tube around the guidewire tube.
The steps of preparing (including, for example, crimping, trimming or cutting), placing and fusing the tubular members in proper alignment are labor intensive, creating costs in terms of labor, time and quality assurance. This is particularly so given the small size of the various pieces of the final SOE product.